Wednesday, October 22, 2014

Stephen Hawking vs Luke Barnes: Multiverses, Fine-Tuning, and the Anthropic Principle

A friend asked me to comment on the article, Stephen Hawking and Leonard Mlodinow's Inadvertent Proof for God.  Since I am not a cosmologist, I shall present instead two points of view: (1) Hawking and Multiverses and (2) Barnes and the Anthropic Principle.  Stephen Hawking is a theoretical physicist and cosmologist at the University of Cambridge.  He is the the best-selling author of the book, Brief History of Time. Luke Barnes, on the other hand, is a post-doctoral fellow at the Sydney Institute for Astronomy in University of Sydney.  Technically, Barnes was not replying to Hawking directly in his paper on Fine Tuning of the Universe for Intelligent Life, but to another Atheist physicist, Victor Stenger, who wrote God: the Failed Hypothesis: How Science Shows that God Does Not Exist. But I think he has summarized the theories and arguments well enough in his 76-page Arxiv paper that we can use his statements as response to Hawking's claim that multiverse theory can explain fine-tuning in our universe.

A. Hawking and Multiverses

In his last year's talk at California Institute of Technology, Stephen Hawking discussed the M-theory:
This theory posits that, when the universe grew exponentially in the first tiny fraction of a second after the Big Bang, some parts of space-time expanded more quickly than others. This could have created "bubbles" of space-time that then developed into other universes. The known universe has its own laws of physics, while other universes could have different laws, according to the multiverse concept. (Space.com)
Hawking and Mlodinow explains further in their book, Grand Design:
“[Just] as Darwin and Wallace explained how the apparently miraculous design of living forms could appear without intervention by a supreme being, the multiverse concept can explain the fine tuning of physical law without the need for a benevolent creator who made the Universe for our benefit. Because there is a law like gravity, the Universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the Universe exists, why we exist.”

...According to M-theory, ours is not the only universe. Instead M-theory predicts that a great many universes were created out of nothing. Their creation does not require the intervention of some supernatural being or god. Rather these multiple universes arise naturally from physical law.” (Word on Fire) (Bold font mine.)
So essentially, M-theory posits a multiverse or a collection of non-interacting universes that began a few seconds after Big Bang, with each universe complete by itself governed by its own physical laws.  The reason why this particular universe that we have supports life as we know it is just due to lottery: because of the many possible universes that could have been created, it just so happened that one universe made our human existence possible and this is our universe.

But let's backtrack a bit.  What Hawking is trying to argue against is the Anthropic Principle.

B. Barnes and the Anthropic Principle

There are two forms of Anthropic Principles--strong and weak.  Let us just discuss the Weak Anthropic Principle:
Weak anthropic principle (WAP) (Barrow and Tipler): "The observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirements that the Universe be old enough for it to have already done so."[21] Unlike Carter they restrict the principle to carbon-based life, rather than just "observers." A more important difference is that they apply the WAP to the fundamental physical constants, such as the fine structure constant, the number of spacetime dimensions, and the cosmological constant — topics that fall under Carter's SAP. (Wikipedia: Anthropic Principle)
Luke Barnes (2012) wrote an ArXiv paper in response to critics of anti-Anthropic Principle: A Fine Tuning of the Universe for Intelligent Life.  His discussion is more for physicists, but here is something about stars:
Stars are defined by the forces that hold them in balance. The crushing force of gravity is held at bay by thermal and radiation pressure. The pressure is sourced by thermal reactions at the centre of the star, which balance the energy lost to radiation. Stars thus require a balance between two very different forces — gravity and the strong force — with the electromagnetic force (in the form of electron scattering opacity) providing the link between the two. There is a window of opportunity for stars — too small and they won’t be able to ignite and sustain nuclear fusion at their cores, being supported against gravity by degeneracy rather than thermal pressure; too large and radiation pressure will dominate over thermal pressure, allowing unstable pulsations.
Regarding multiverses, Barnes concludes:
We conclude that the universe is fine-tuned for the existence of life. Of all the ways that the laws of nature, constants of physics and initial conditions of the universe could have been, only a very small subset permits the existence of intelligent life. 
Will future progress in fundamental physics solve the problem of the fine-tuning of the universe for intelligent life, without the need for a multiverse? There are a few ways that this could happen. We could discover that the set of life-permitting universes is much larger than previously thought. This is unlikely, since the physics relevant to life is low-energy physics, and thus well-understood. Physics at the Planck scale will not rewrite the standard model of particle physics. It is sometimes objected that we do not have an adequate definition of ‘an observer’, and we do not know all possible forms of life. This is reason for caution, but not a fatal flaw of fine-tuning. If the strong force were weaker, the periodic table would consist of only hydrogen. We do not need a rigorous definition of life to reasonably conclude that a universe with one chemical reaction (2H → H2) would not be able to create and sustain the complexity necessary for life. 
Alternatively, we could discover that the set of possible universes is much smaller than we thought. This scenario is much more interesting. What if, when we really understand the laws of nature, we will realise that they could not have been different? We must be clear about the claim being made. If the claim is that the laws of nature are fixed by logical and mathematical necessity, then this is demonstrably wrong — theoretical physicists find it rather easy to describe alternative universes that are free from logical contradiction (Davies, in Manson, 2003). The category of “physically possible” isn’t much help either, as the laws of nature tell us what is physically possible, but not which laws are possible.

C. Conclusions: Anthropic Principle and Christianity

Proponents of the Anthropic Principle like Barnes only claims that our universe is fine-tuned in order to support intelligent life.  Whether God is responsible for this fine-tuning cannot be argued from this argument, but this does not at the same time rule out a Creator in the Christian tradition who made the Universe in His Infinite Wisdom and sees that it was good.  The universe was created because of Man: to provide an garden for him in space and time, and to provide the "dust" from which God shall fashion man in His image and likeness.

Because of the strong link between the Anthropic Principle and Creationism, Atheist physicists like Hawking direct their energies to refuting the Principle or lessening its power, by arguing, for example, that our universe is not really special, because other universes could have sprung into being which may or may not support intelligent life like ours.  In doing so, they hope to argue against the existence of God as well.

To Atheists, human life is without purpose, since we are just accidents in space-time created by some random universe.  It is an unhappy thought.  And it can drive some to commit suicide in despair.  But if the universe was not a random thing but designed and fine-tuned for human life, then perhaps human life has a purpose: to know and understand the universe in order to get a glimpse of the infinite beauty and intelligence of the Creator who awaits us with love in the next life.  And that is a happy thought.

A Brief History of Time
A Brief History of Time
The Grand Design
The Grand Design
The Universe in a Nutshell
The Universe in a Nutshell
God: The Failed Hypothesis. How Science Shows That God Does Not Exist
God: The Failed Hypothesis. How Science Shows That God Does Not Exist
The Fallacy of Fine-Tuning: Why the Universe Is Not Designed for Us
The Fallacy of Fine-Tuning: Why the Universe Is Not Designed for Us
The Anthropic Cosmological Principle (Oxford Paperbacks)
The Anthropic Cosmological Principle (Oxford Paperbacks)
The Physics of Christianity
The Physics of Christianity
555 77 855
555 77 855